Determine Data Buffer Size in Oracle9i

The ability to compute the optimal size of data buffers is a critical task for large databases. As databases grow to hundreds of billions of bytes, it becomes economically impractical to cache the entire database in RAM. So Oracle professionals must find the point of diminishing marginal returns for the addition of RAM resources. Being able to do this can save a company hundreds of thousands of dollars in RAM expenses.

Oracle9i introduces a new view, v$db_cache_advice, that can predict the benefit of additional data buffers in the data buffer cache. This view shows the estimated miss rates for twenty potential buffer cache sizes, ranging from 10 percent of the current size to 200 percent of the current size. This allows Oracle DBAs to accurately predict the optimal size for the RAM data buffer.